I have a 100+ year old home. I want to update the heating system but have no space for ductwork. I was told that a high presseure system exists for homes that have no space for ductwork. Please any advice would be appreciated. I have a hot water boiler at this time but want to also be able to cool in the summer.

Have you talked to a H/A contractor yet? If not, give that a try first. While you may not see any obvious way to install ductwork in your house, there are many inventive ways to make it happen. If you want to add A/C you are going to need a forced air system with ductwork, makes sense to have the heat be via ducts too.

Talk to one or two H/A companies, especially look for ones who work on remodels rather than just new construction. Or, search around for a good remodeling General Contractor to plan out the duct runs and any chases needed. While it's not always easy or obvious, I have yet to find a house that we could not convert to a forced air system.

the impression I got from a Holmes episode was high pressure heating is not easily done. in other words, he didn't flat out say "unacceptable," but every other reference did.

if you have 2x4 walls and floor joists, you can put in forced air heat/cooling with standard products, well understood, with good computer planner products in the trade. might be some wall repair afterwards, but you won't notice it when done.

Probably the most practical solution is to buy window air conditioners for your house.

Check these systems out. Call and a representative will tell you exactly what you need for your house. It's much cheaper then running ducts and by far easier to install. One compressor can handle up to 4 units using heat and AC. Do an internet search and compare different companies etc..
http://www.minisplitsystems.com/